Got a lot of rust to fix in the floors, I'm just going to weld in new patches where the big holes are. First problem.... Killing the rust where it has not rusted all the way through, but I need to be able to weld through it also, so what would be the best stuff? I don't know if the POR 15 (and related products) are weldable after using? I've seen "weld through primer" (Eastwood?) I quess some sort of jelly rust killers would really do the trick, but I don't want to have to wash the area where I killed the rust. Also, on the weld through primer, is there any local place to get it? I know it won't kill the rust, but I want to try to prevent it from coming back.
JMO I would cut out around the real bad area's then media blast all around the cut out to remove as much rust as possible then weld in your patch panels then use Eastwood's rust system. It is a Rust Converter then Rust Encapsulator then a good Top Coat of your choice. Good Luck
Found some phosphoric Prep and Etch at Home Depot today, going to try using it on the rust, then Rustoleum Heavy Rust primer, the top coat with Rustoleum color. Lots of little cracks to weld, and replace the damage. I'm a little scared of the other rust treatments, they say don't use it where there is no rust, as it may cause rust.
If you use acid to etch the metal then you have to neutralize the acid before you coat it or it will continue to attack the metal. Sand it until it is bright after cutting out major rust areas. Fit a patch and weld it in. Note: if you use a backer of copper (heavy copper block behind your weld) it will reduce the blow through problem. Weld short lines slowly working back and forth until you completely close it up. Prime the metal with a primer sealer and then what ever rust proofing / undercoating that you are going to use.
